1. Field of the Invention
The present invention relates to a preparation method of Zeolitic Imidazolate Framework-90 (ZIF-90) in water-based system and, more particularly, to a preparation method of ZIF-90 using water as solvent.
2. Description of Related Art
Metal-organic Frameworks (MOFs) is a novel organic-inorganic hybrid material which has an inorganic metal functioning as the center, and has organic functional groups covalently or ionically bonded to the inorganic metal to form a regular porous structure. Most of the MOFs have high porosity and high specific surface area, thus the MOFs have high gas adsorption capacity. According to the different porous size of the MOFs, it can be used as a filter for gaseous molecules having different sizes.
Zeolitic Imidazolate Frameworks (ZIFs) is an MOFs material with high thermal stability. The porous size of the ZIFs can be controlled via surface modification or the type of the modified functional groups on the surface of ZIFs, and thus giving different physical and chemical properties to the material. Therefore, the ZIFs can be further applied in the fields of gas storage, catalysis, molecule separation, or other applications.
Among the ZIFs, Zeolitic Imidazolate Framework-90 (ZIF-90) has carbon-oxygen double bonds which provide good non-covalent attraction between carbon dioxide. In addition, the pore size of ZIF-90 is about 0.35 nm, which is more beneficial for CO2 selection and for the absorption of CO2 to mitigate the environmental impact for greenhouse gases. Moreover, according to the relevant researches, 83 liter of gaseous CO2 can be absorbed by 1 liter of ZIF-90. Moreover, ZIF-90 is non-toxic and easy to be produced. Thus, ZIF-90 is considered as a potential material for absorbing CO2.
However, organic solvents are often used in most of the current conventional preparatory methods for ZIF-90, and the waste produced by mass production of ZIF-90 also becomes a burden to the environment. Therefore, in order to meet the requirements of green chemistry process, a novel preparation method of ZIFs is needed for mass production of ZIF-90, in which the ZIF-90 is synthesized under aqueous conditions, and the environmental pollution caused during preparation is significantly reduced.
The present invention provides a preparation method of Zeolitic Imidazolate Framework-90 (ZIF-90) in water-based system, which is different from the conventional preparation methods that use organic solvent, such as DMF or DEF, and thus significantly reduced the impact to the environment.